2010 R56 CooperS 50k miles. High pitched whirring sound audible in the cabin
when I accelerate.
What is it where is it coming from

 

Could not begin to imagine. Not much to go on there and at first I thought it was a joke? Could be anything from a bearing i.e. anything driven by the auxiliary belt, the belt itself, the diferential/gearbox, wheel bearing, being followed by a helicopter? In your head? Bit more input please.